Preferences, Broadcast, Profile, Plugins windows are always opened at the same position and are not saving their sizes. It seems that these windows has to be opened in center of main roster window. So if roster window is in lower right corner, then Preferences window will open in lower-right corner too. In some cases window can get out of bounds of the display, so one would have to drag a window up to be able to press Close button. Saving the size of Broadcast window could be handy too.